JPS6262594A - Mounting method for electronic part with lead - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method for mounting leaded electronic components.

[Technical background of the invention and its problems] The development of the semiconductor industry is remarkable, and the development of high-performance semiconductor elements has led to a wide range of applied products. For each applied product, we design unique circuit wiring on printed wiring boards. In this way, even in the field of applied products that use semiconductors, we design our own circuits and implement factory automation (FA).
) to support mass production. This kind of FA
Fully automatic mounters for attaching electronic components using adhesives in systems, fully automatic bonders for wiring between IC bonding pads and printed circuit boards, and bonding pads for ICs have become highly developed. However, in fully automated soldering technology, one set of soldering molds must be positioned on the pre-soldered pattern of the printed circuit board and transferred, and then the bar-shaped heater chips are placed on the multiple arrayed boards. (soldering iron)
Due to this, when heating and pressing, during a large number of soldering operations, preliminary soldering of printed wiring boards may be soldered out of alignment with the pattern.

This is because the width of the IC lead and the pre-solder on the printed wiring board are almost the same, and the distance between them is about one lead.

This will result in poor insulation.

The yield rate worsens as the soldering speed increases in order to improve productivity. The larger the printed wiring board with a larger number of parts, the greater the problem of improving the yield.

One idea to improve this problem is to form recesses in the pre-soldered parts of printed wiring boards, but as the density of printed wiring patterns increases and the number of leads in flat package ICs increases, it becomes difficult to form recesses in practice. Improvements were requested.

[Purpose of the invention]

This invention was made in response to the above points.

The present invention provides a method for mounting electronic components with leads, which reduces misalignment during the melting process and improves the yield of desired wiring parts even with a high-density printed wiring pattern.

[Summary of the invention]

That is, when mounting the electronic component leads on the wiring portions of the printed wiring board, there are two steps: forming recesses in each of the wiring portions in advance by photoetching, and mounting the electronic component leads by engaging them in the recesses. The present invention provides a method for mounting an electronic component with leads.

[Embodiments of the invention]

Next, an embodiment in which the method of the present invention is applied to soldering electronic components to a printed wiring board will be described with reference to the drawings.

Wires (2) are selectively formed on the surface of an insulating substrate, such as a glass epoxy resin substrate (1), using circuit board manufacturing technology, and solder resist (3) is used to solder these wires (2) so that only the parts are exposed. is formed, and a printed wiring board (4) is formed. Further, cream solder is applied to the soldering parts of the wiring board (4), and the applied state is exposed in a high temperature bath (not shown) for a predetermined period of time. Through this process, preliminary solder (5) consisting of cream solder 71) is formed only at the soldering points. Figure 1 (A) and Figure 1 (B)
, The pre-soldering of the flat package type ICt6) not shown in (C) shows the butter/(force. Figure 1 (B) is a front view, and Figure 1 (C) is a side view. The structure of the packaged IC (6) is well known to those skilled in the art, and a large number of leads (9) are provided from the side wall of the molded body (8), for example, from two sides, and these leads (9) are arranged as shown in FIG.
As shown in C), it is bent in the middle so that the tip αυ forms the same plane as the bottom surface of the mold body (8). Flat package with this structure 3
The iIC (6) is soldered to the printed wiring board (4), and this is done as follows in the embodiment of the present invention. That is, a part of the formed preliminary solder part (5), for example, the soldering of the lead (9) of the IC (8) is part 01).
Place a recess in the part of the printed wiring board that will be engaged by the pre-solder (for example
5) is partially removed to form a region α2, that is, a concave portion. This state is shown in FIG. 1(C)(B). When mounting the IC (81), it is desirable that the area (14) for soldering the leads (9) be larger than the area where the portions αυ are in contact with each other.

To form this region (L), solder all the preliminary solder parts (5) on the printed wiring board by selectively photo-etching only the area a where part αυ engages.This can be done easily by patterning in advance. It can be formed by depositing a photoresist on the surface and patterning this photoresist.In other words, it can be formed simultaneously on a single printed wiring board, and microfabrication can be easily formed. It is also possible to selectively and easily form recesses according to the shape and size of After applying the soldering lead (9), part I is engaged and placed.

In this process, after positioning the IC (8), it is automatically transported and placed by a tltlc robot at a position taught in advance according to a pre-stored program. In this state, −
A preheated heater tip (soldering iron) (not shown) with a rod-shaped tip that straddles the group of leads (9) on the side is pressed. At the same time as this pressing, increase the heating current.

Melt the preliminary solder (5) and solder the leads (9) of the IC (6). Since the soldering is performed by engaging the concave portion in this manner, the solder is positioned by the side wall of the concave portion a, and the lateral displacement that occurs when the preliminary solder (5) is melted can be improved. In particular, in this embodiment, the soldering is done at αυ
The preliminary solder (5) on the engaging part is completely removed,
Since it is placed on the flat wiring (2), it has the effect of greatly improving one positional deviation.

As explained above, a recess is formed in the preliminary solder portion by photo-etching, and the IC leads are engaged with the recess and soldered, so that positional displacement can be reduced. Pre-solder is used when soldering electronic components to the printed wiring board (4).
When soldering the printed wiring board (4), a method is used in which solder is formed on the parts in advance, and this refers to the solder that is formed in advance. One surface of this solder has a smooth arc shape, and the formation of recesses is effective.

〔Effect of the invention〕

As described above, according to the present invention, a recess is formed by photo-etching, and the lead of an electronic component is engaged with the recess for mounting, thereby reducing misalignment during mounting, for example, in the solder melting process.

This is effective in improving yield reduction due to positional misalignment.

In particular, it is possible to form recesses even when the distance between the pinches is as small as, for example, 0.65131.

In the above embodiment, a flat package type I is used as an electronic component.
Although we have explained about C, any method may be used as long as it is used for soldering electronic component leads.For example, an abrasive.

Any transistor capacitor or the like may be used.

In the above embodiment, an example of a lead having a rectangular cross section in a flat package type IC has been described, but the same effect can be obtained regardless of the cross-sectional shape of the lead, even if the lead has a circular cross-section as in an electrolytic capacitor. In the case of a lead with a circular cross section, the recess is formed in a curved shape.

Even better positioning.

[Brief explanation of drawings]

FIG. 1 (A) (BXCXD) (E) is an explanatory diagram of an embodiment of the method of the present invention. 1... Board →... Printed wiring board 5...
Pre-soldering 7...Soldering is pattern 9...Lead 11...Soldering is part 1
2...Fourth Division Agent Patent Attorney Nori Ken Chika Yudo Kikuo Takehana (A) (B) (C) (E) Figure 1

Claims (2)

[Claims] (1) When mounting the electronic component leads on the wiring portions of the printed wiring board, there is a step of forming recesses in each of the wiring portions in advance by photo-etching, and mounting the electronic component leads by engaging them in the recesses. A method for mounting a leaded electronic component, comprising the steps of: (2) The means for mounting electronic component leads in the recesses formed by photo-etching consists of a step of solder plating the recesses, a step of applying flux to the solder-plated recesses, and a step of applying flux to the recesses to which the solder has been applied. The lead according to claim 1, comprising the steps of: engaging a lead of an electronic component with the recess; and applying pressure and heat with a heater chip from above the lead engaged with the recess. How to mount electronic components with